Nanotechnology Now

Our NanoNews Digest Sponsors


Heifer International

Wikipedia Affiliate Button

Home > Press > New System for Detection of Single Atoms

Abstract:
Scientists have devised a new technique for real-time detection of freely moving individual neutral atoms that is more than 99.7% accurate and sensitive enough to discern the arrival of a single atom in less than one-millionth of a second, about 20 times faster than the best previous methods.

New System for Detection of Single Atoms

College Park, MD | Posted on December 4th, 2009

The system, described in Advance Online Publication at the Nature Physics web site by researchers at the Joint Quantum Institute (JQI) in College Park, MD, and the Universidad de Concepción in Chile, employs a novel means of altering the polarization of laser light trapped between two highly-reflective mirrors, in effect letting the scientists "see" atoms passing through by the individual photons that they scatter.

The ability to detect single atoms and molecules is essential to progress in many areas, including quantum information research, chemical detection and biochemical analysis.

"Existing protocols have been too slow to detect moving atoms, making it difficult to do something to them before they are gone. Our work relaxes that speed constraint," says coauthor David Norris of JQI. "Moreover, it is hard to distinguish between a genuine detection and a random 'false positive' without collecting data over a large period of time. Our system both filters the signal and reduces the detection time."

The scientists trap and cool a small population of atoms (rubidium is used in the current experiment) in a vacuum enclosure in such a way that they drop slowly, one at a time, through a hole 1.5 millimeters wide at the bottom of the trap. The atom then falls about 8 centimeters until it enters a tiny chamber, or cavity, that is fitted on opposite sides with highly reflective mirrors that face one another at a distance of about 2 millimeters. Passing through the center of both mirrors is a laser beam of wavelength 780 nanometers - just slightly longer than visible red light. The beam excites the atom as it falls between the mirrors, causing it to reradiate the light in all directions.

That arrangement is a familiar one for labs studying the interaction of atoms and photons. The JQI system, however, has two distinctively unique features.

First, the researchers use two polarizations of cavity light simultaneously: one (horizontal) which is pumped in to efficiently excite the atoms, and the other (vertical) which only appears when emitted by an atom inside the cavity. Although the descent of the atom through the chamber takes only 5 millionths of a second, that is 200 times longer than it takes for the atom to become excited and shed a photon, so this process can happen multiple times before the atom is gone.

Second, they create a magnetic field inside the cavity, which causes the laser light polarization to rotate slightly when an atom is present. Known as the Faraday effect, this phenomenon is typically very weak when observed with a single atom. However, since the light reflecting between the mirrors passes by the atom about 10,000 times, the result is a much larger rotation of a few degrees. This puts significantly more of the laser light into the vertical polarization, making the atoms easier to "see."

The light eventually escapes from the cavity and is fed through a polarizing beamsplitter which routes photons with horizontal polarization to one detector, and vertical polarization to another. Each arriving photon generates a unique time stamp whenever it triggers its detector.

Although the detector for the vertically polarized light should only be sensitive to light coming from an atom in the cavity, it can be fooled occasionally by stray light in the room. But because there are multiple emissions from each atom, there will be a burst of photons whenever an atom passes between the mirrors. This is the signature that the researchers use to confirm an atom detection.

"The chief difficulty lies in verifying that our detector is really sensitive enough to see single atoms, and not just large groups of them," says team leader Luis A. Orozco of JQI. "Fortunately, the statistics of the light serve as a fingerprint for single-atom emission, and we were able to utilize that information in our system."

* "Photon Burst Detection of Single Atoms in an Optical Cavity," M.L. Terraciano, R. Olson Knell, D.G. Norris, J. Jing, A. Fernandez and L.A. Orozco, www.nature.com/nphys/index.html, DOI 10.1038/NPHYS1282.

####

About Joint Quantum Institute, University of Maryland
The Joint Quantum Institute is a research partnership between University of Maryland (UMD) and the National Institute of Standards and Technology, with the support and participation of the Laboratory for Physical Sciences.

Created in 2006 to pursue theoretical and experimental studies of quantum physics in the context of information science and technology, JQI is located on UMD's College Park campus.

For more information, please click here

Contacts:
JQI General Info:
Curt Suplee
301.405.2291

or send e-mail to

Copyright © Joint Quantum Institute

If you have a comment, please Contact us.

Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

Bookmark:
Delicious Digg Newsvine Google Yahoo Reddit Magnoliacom Furl Facebook

Related News Press

News and information

New remote-controlled microrobots for medical operations July 23rd, 2016

New superconducting coil improves MRI performance: UH-led research offers higher resolution, shorter scan time July 23rd, 2016

New probe developed for improved high resolution measurement of brain temperature: Improved accuracy could allow researchers to measure brain temperature in times of trauma when small deviations in temperature can lead to additional brain injury July 23rd, 2016

Quantum drag:University of Iowa physicist says current in one iron magnetic sheet can create quantized spin waves in another, separate sheet July 22nd, 2016

Chemistry

New reaction for the synthesis of nanostructures July 21st, 2016

Pushing a single-molecule switch: An international team of researchers from Donostia International Physics Center, Fritz-Haber Institute of the Max Planck Society, University of Liverpool, and the Polish Academy of Sciences has shown a new way to operate a single-molecule switch July 19th, 2016

Rice's 'antenna-reactor' catalysts offer best of both worlds: Technology marries light-harvesting nanoantennas to high-reaction-rate catalysts July 18th, 2016

Researchers improve catalyst efficiency for clean industries: Method reduces use of expensive platinum July 8th, 2016

Sensors

Electron 'spin control' of levitated nanodiamonds could bring advances in sensors, quantum information processing July 20th, 2016

Easier, faster, cheaper: A full-filling approach to making nanotubes of consistent quality: Approach opens a straightforward route for engineering the properties of single-wall carbon nanotubes July 19th, 2016

Researchers invent 'smart' thread that collects diagnostic data when sutured into tissue: Advances could pave way for new generation of implantable and wearable diagnostics July 18th, 2016

UNIST engineers octopus-inspired smart adhesive pads July 15th, 2016

Announcements

New remote-controlled microrobots for medical operations July 23rd, 2016

New superconducting coil improves MRI performance: UH-led research offers higher resolution, shorter scan time July 23rd, 2016

New probe developed for improved high resolution measurement of brain temperature: Improved accuracy could allow researchers to measure brain temperature in times of trauma when small deviations in temperature can lead to additional brain injury July 23rd, 2016

Quantum drag:University of Iowa physicist says current in one iron magnetic sheet can create quantized spin waves in another, separate sheet July 22nd, 2016

Tools

New superconducting coil improves MRI performance: UH-led research offers higher resolution, shorter scan time July 23rd, 2016

The birth of quantum holography: Making holograms of single light particles! July 21st, 2016

Nanometrics Announces Upcoming Investor Events July 20th, 2016

A mini-antenna for the data processing of tomorrow: Nature Nanotechnology: Short-wavelength spin waves generated directly for the first time July 20th, 2016

Quantum nanoscience

Quantum drag:University of Iowa physicist says current in one iron magnetic sheet can create quantized spin waves in another, separate sheet July 22nd, 2016

A new spin on reality July 15th, 2016

Physicists couple distant nuclear spins using a single electron: For the first time, researchers at the University of Basel have coupled the nuclear spins of distant atoms using just a single electron July 12th, 2016

Quantum technologies to revolutionize 21st century: Nobel Laureates to discuss impacts at 66th Lindau Meeting July 5th, 2016

NanoNews-Digest
The latest news from around the world, FREE




  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoTech-Transfer
University Technology Transfer & Patents
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More











ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project







Car Brands
Buy website traffic